Vacuum-Assisted Closure Therapy after Cardiac Surgery. Sternal Stability, Cost of Care, Learning Curve and Hemodynamic Outcome

University dissertation from Thoracic Surgery

Abstract: Deep sternal wound infection (DSWI) following cardiothoracic surgery is a rare but potentially life-threatening complication with high morbidity and mortality. DSWI is associated with a significant increase in the length of hospital stay and the cost of hospitalization. The socioeconomic impact of DSWI is considerable. Conventional treatment includes reexploration, surgical debridement, mediastinal antibiotic irrigation-suction, primary or delayed sternal closure, and reconstructive procedures with vascularized tissue flaps. Despite these efforts, patients with DSWI have poor long-term outcome following conventional treatment. Vacuum-assisted closure (VAC) therapy is a new modality for the treatment of problematic chest wound healing. This technique can be performed with less surgical trauma and has been adopted as the standard treatment for DSWI because of its excellent clinical outcome. However, many questions remain concerning VAC therapy, such as the optimal subatmospheric pressure, cost-effectiveness, learning curve effects, survival and changes in hemodynamics. The aims of this work were: (1) to evaluate sternal stability at different negative pressures during VAC therapy; (2) to investigate whether high negative pressures increase the rate of organ rupture (e.g. heart and lungs); (3) to calculate the cost of VAC treatment in patients with DSWI after cardiac surgery; (4) to ascertain whether there is any correlation between the preoperative EuroSCORE and the cost of DSWI therapy; (5) to identify possible effects of the learning curve on survival during the introduction of VAC therapy in patients with DSWI and predictors of late mortality; and finally (6) to investigate changes in the hemodynamics during the application of negative pressure therapy. We found that low negative pressures (–50 to –100 mmHg) stabilize the sternum just as efficiently as high negative pressures (–150 to –200 mmHg). No failure of the foam dressings or organ ruptures were seen following the application of low negative pressures in combination with high lateral forces (above 200 N). VAC therapy in patients with DSWI following cardiac surgery seems to be cost-effective and no correlations were found between the preoperative EuroSCORE and the cost of DSWI therapy after CABG surgery. VAC therapy is thus an excellent adjunct for wound healing in DSWI without significant learning curve effects on early or late mortality. Late diagnosis and prolonged wound therapy were identified as predictors of late mortality. With a suitable foam application technique, a pressure of –75 mmHg can be applied without compromising the central hemodynamics.